presence of aflatoxins in smoked-dried fish sold in abeokuta, ogun ...

(Adhikari et al., 2004). This finding confirmed result of an earlier study which suggested that
malarial infections were increased in children exposed to aflatoxin, as determined on the basis of
the amounts of aflatoxin–albumin adducts (Allen et al., 1992). However, a similar study from the
Philippines gave inconclusive results (Denning et al., 1995).
2.7.1 Immuno-suppression
Studies on the immunosuppressive effects of aflatoxins published before 1993 were reviewed in
the previous monograph (IARC, 1993). Aflatoxins modulate the immune system in domestic and
laboratory animals after dietary intake of up to several milligrams per kg feed (Hall and Wild,
1994; Bondy and Pestka, 2000). The major effects involve suppression of cell-mediated
immunity, most notably impairment of delayed-type hypersensitivity, which has been a
consistent observation at low dose levels in various species (Bondy and Pestka, 2000). Other
notable effects include suppression of non-specific humoral substances, reduced antibody
formation, suppression of allograft rejection, decreased phagocytic activity and decreased
blastogenic response to mitogens (WHO, 1990). Strong modification of cytokine secretion and
interleukin gene expression has also been observed in vitro with mycotoxins, including
aflatoxins (Han et al., 1999). The immune system of developing pigs was affected by maternal
dietary exposure to aflatoxin B1 or aflatoxin G1 during gestation and lactation. Motility and
chemotaxis of neutrophils were inhibited in piglets from aflatoxin-treated sows (Silvotti et al.,
1997). In a further study, thymic cortical lymphocytes were depleted and thymus weight was
reduced in piglets from sows exposed to aflatoxin B1 (800 ppb in diet) from day 60 of gestation
up to day 28 of lactation (Mocchegiani et al., 1998).
The effects of aflatoxin B1 on growing rats have been shown to be similar to those in adult
animals. Weanling rats [strain unspecified] were given oral doses of 60, 300 or 600 µg/kg body
weight aflatoxin B1 in corn oil every other day for four weeks. Aflatoxin B1 selectively
suppressed cell-mediated immunity, assessed by measuring the delayed-type hypersensitivity
response, at the 300- and 600-µg/kg body weight doses (Raisuddin et al., 1993).
In order to determine the effect of aflatoxin B1 on the activation of toxoplasmosis, CF1 mice
were injected with the cyst-forming parasite Toxoplasma gondii one month before aflatoxin B1
was given by gavage daily for 50 days at 100 µg/kg body weight. Cysts developed in the brains
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